In current memory cell arrays, memory cells in a row of the array are connected to a single wordline for activating the memory cells. For example, in a typical Dynamic Random Access memory (DRAM) cell array as illustrated in FIG. 1, DRAM cells of row 131 are connected to and activated by wordline 170. A critical constraint on this type of design is that, regardless of the user's intention, the wordline activates all memory cells of the row simultaneously for writing the intended memory cells during a writing cycle. Consequently, the timing of write events is highly correlated. This time-correlation may cause artifacts, such as dynamic-false-contouring (DFC) in display systems that employ memory cell arrays for controlling the pixels of the display systems and pulse-width-modulation (PWM) technique for displaying gray-scales of images.
As a way of example, FIGS. 2a to 2d illustrate the formation of DFC artifacts in the boundary of two neighboring pixels that are controlled by two neighboring memory cells sharing one wordline. Referring to FIG. 2a, pixels 351 and 353 are two neighboring pixels of the display system and are controlled by two neighboring memory cell, such as memory cells 191 and 193 in FIG. 1. Assuming that gray-scaled images of an object traversing from left to right are to be displayed by the two pixels, illumination intensities of the two pixels are modulated using PWM waveforms such that, in the screen (pixel) coordinate, the averaged illumination intensity over a frame duration T of each pixel corresponds to the desired grayscale of the image. As viewed by stationary human eyes, the difference of the averaged illumination intensity at the boundary of the two pixels is perceived as the contour of the object, as shown in FIG. 2b. 
However, the contour of the object will be distorted in the retina coordinate in viewer's eye when the eyes move with the object. FIG. 2c presents the two pixels in the retina coordinate that moves with the eyes and the object. As can be seen, the pixels are distorted. The boundary of the two pixels is extended into a region, in which the averaged illumination intensity varies with position, as shown in FIG. 2d. This variation of the averaged illumination intensity will be perceived and recognized by the eyes as “real” contour of the object. This phenomenon is generally referred to as DFC artifact.
Therefore, methods and apparatus are desired for decorrelating the memory cells and associated pixels of a spatial light modulator such that the DFC like artifacts can be effectively reduced, if not removable.